Analog pins A1-A5 were enabled for
digital function to provide temperature
sensor power and communication.
Fortunately, this leaves digital pins 3 and 11
(both on 16-bit TIMER2) available to use
for Pulse Width Modulation (PWM)
outputs: pin 11 to heat (plus +); pin 3 to
cool (minus -). Two optional LEDs provide a
visual indication of PID variable outputs.
An Arduino Nano and breadboard were
used for actual SSR bench testing purposes.

1602 LCD Keypad Display Shield

This is a popular Arduino shield that integrates a 16-
character by two-line LCD display with five navigation
buttons and one reset button. This hardware is supported
in the standard Arduino IDE library. Simply #include
<LiquidCrystal.h> in your sketch.